1. Field of the Invention
This invention relates in general to hydraulic couplings, and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, this invention involves a hydraulic coupling having a bleed port allowing seawater to enter the bore of the female coupling member during disassembly.
2. Description of Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member with sealed fluid passageways connecting therebetween. The female member generally is a cylindrical body with a relatively large diameter longitudinal bore at one end, and a relatively small diameter longitudinal bore at the other. The small bore facilitates connection to hydraulic lines, while the large bore seals and slidingly engages the male member of the coupling. The male member includes a cylindrical portion at one end having an outer diameter approximately equal to the diameter of the large bore of the female member of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to various embodiments of the device, fluid flow is established between the male and female members.
In the use of undersea couplings, the male and female members may be interconnected or disconnected while the coupling remains underwater, either manually by a diver or automatically by a diverless system such as a remote operating vehicle (ROV) as is well known to those skilled in the art. The male member and the female member are generally connected to opposing plates of a manifold and are held together by bolts or hydraulic members attached to the plates of the manifolds. The male member is commonly attached to one plate, while the female member is attached to an opposing plate so as to face the male member and align with it. The male member and female member may be attached to the manifold plates using various means, such as set screws or threads. Techniques for attaching the members to such manifold plates are well known to those skilled in the art.
In couplings of the foregoing type, one or both coupling members may include a poppet valve which opens to allow fluid flow, and closes against a valve seat within the coupling member to arrest the flow. Generally, the poppet valves are spring-biased to the closed position. The poppet valves each include a valve actuator which may be a nose or stem extending from the apex of the valve face along the longitudinal axis of the poppet valve.
Undersea hydraulic couplings of the foregoing type are connected and disconnected while subsea. In emergency situations, for example, storms, hurricanes, etc., the coupling members must be quickly disconnected and one of the members, typically the female member, removed from the subsea location. When the male member is withdrawn from the large central bore of the female member, there is a resulting low pressure area or vacuum created within the bore. The vacuum increases the difficulty of disengaging the male member from the female member of the coupling. This resistance to disengagement due to the vacuum is magnified when multiple couplings and manifold plates are disengaged. In recent years, undersea drilling and production is at increasingly greater depths, i.e., 5,000 or more feet below sea level.
At greater ocean depths, the hydraulic pressure of the system of which the coupling is a part must be greater. For example, the pressure of the hydraulic system typically must exceed the pressure of the hydrocarbon in the well bore. In subsea applications at increased internal pressures, it is necessary to prevent leakage of hydraulic fluid from the system while the coupling members are engaged or disengaged. Therefore, one or more seals are used for the junction between the coupling members. Specifically, elastomeric seals and pressure-energized metal seals have been used in undersea hydraulic couplings.
In U.S. Pat. No. 4,813,454 to Robert E. Smith III, an undersea coupling with pressure balancing ports is shown. The male member of the coupling includes at least one balancing port communicating between the leading face and outer sidewall. When the male member is sealed in relation to the annular elastomeric seal in the receiving chamber of the female member, and the poppet valves of each member are closed, the balancing port is used to bleed sea water into or out from the annulus between the coupling members.
In U.S. Pat. No. 5,469,887 to Robert E. Smith III, a hydraulic coupling with a pressure equalizing valve is shown between the central bore or receiving chamber of the female member and the external surface of the female member. A valve in the passage allows sea water to flow into the annulus during connection or disconnection of the male and female coupling members, thus equalizing the pressure and preventing implosion of seals during disconnection of the coupling members.